A home fan usually includes a rotary shaft, a set of blades or an impeller rotating around the shaft, and driving equipment that drives the blades or the impeller to rotate for generating an air stream. The flow and circulation of air produces wind, and heat may be dissipated by air convection to make the user feel cool. The conventional home fan has the disadvantages that the air stream generated by the rotating blades or impeller cannot be uniformly sensed by the user, so the user has a feeling of “patting” generated by the turbulent airflow. Moreover, the blades occupy a large area and thus lower the room brightness.
A bladeless fan, precisely referred to as “a device for blowing air”, includes a base for generating an air stream and a ring nozzle supported by the base. The ring nozzle defines an opening, and the nozzle includes an inner passage and a mouth for jetting the air stream. The base includes an air intake arranged on the housing of the base and an impeller inside the base. A discharge portion of the impeller and the inner passage of the nozzle are respectively in communication with a pipe in the base. The impeller extracts air through the air intake. The air flows through the pipe in the base and the inner passage of the nozzle, and then an air stream is jetted from the mouth of the nozzle. The patent documents U.S. Pat. No. 2,488,467, CN 101825104, CN 101858355, and CN 101825101 also disclose other fans or circulators which are similar to the above. However, the pitch of the fan or circulator can only be adjusted at a small angle, which fails to satisfy the requirement for adjusting the direction of air stream at a large angle.
In addition, there are a large amount of dust particles suspended in the air, and dusts are known as the “killer” of household appliances because the presence thereof greatly influences the performance of the household appliances. The granular material suspended in the air is composed of solid or liquid micro-particles. The particles suspended in the air include a polydisperse aerosol of solid particles and liquid particles. The conventional bladeless fan is not provided with an air filter device at the air intake, so after a long time of use, the dusts in the air adhere to the impeller, pipes in the base, inner passage, and mouth of the nozzle. Particularly, the structure inside the bladeless fan is complicated due to the structure of the impeller and is hard to disassemble for cleaning. In the absence of the air filter device, an excessive amount of dust will adhere, which adds to the load on the electric motor for driving the impeller and in turn shortens the operational lifespan and increases the energy consumption. Meanwhile, the excessive dust may block the slit of the nozzle so that the nozzle cannot jet the air stream, which in turn shortens the operational lifespan of the fan. Also, hazardous organic substances like formaldehyde, methylamine, benzene, xylene and other pollutants like the radioactive dust Iodine 131, odour and bacteria etc. exist in the air, but the conventional bladeless fan does not have deodorization and air purification functions.
In view of the above, the conventional bladeless fan has obvious inconvenience and defects in use and needs to be improved and perfected.